1. Field of the Invention
The present invention relates to a label sheet out-feeding detection device of a barcode printer, and in particular to a label sheet out-feeding detection device that is switchable between a projecting detection/operation condition and a depressed and stowed condition by simple and resiliently biased depression.
2. The Related Arts
A conventional barcode printer contains a label sheet which is contained inside the barcode printer for printing thereon barcodes by the operation of a printing mechanism and then out-fed. To control the label sheet out-feeding and the feeding precision thereof, a detection device is arranged on a front enclosure of the barcode printer to detect the out feeding condition of the label sheet and provide reference signal on which the printing operation and out feeding operation of the printing mechanism and the barcode printer are based. Thus, the detection precision and sensitivity of the label sheet out-feeding detection device is of importance for the quality of printing and out feeding of the label sheet.
The conventional label sheet out-feeding detection device of the barcode printers is a reflective photo-electric detection device, which occupies an amount of space outside the enclosure of the barcode printer. The reflective photo-electric detection device is susceptible to interference caused by natural light or other light sources, leading to detection error or deterioration of detection sensitivity. Further, in the time period when no label sheet passes therethrough to be detected thereby, the detection device is not shielded and is thus directly exposed to dust contamination and interference caused by the surrounding light or other light sources, leading to false detection caused by error reflection signal and incorrect printing operation and affecting feeding and quality of printing of the label sheet.
The conventional label sheet out-feeding detection device is arranged outside the barcode printer, and thus occupying a space that might be required for operating the barcode printer. This makes the construction of the barcode printer complicated in order to cope with such a space problem, leading to increase of manufacturing costs and adverse factors for market competition.